The O2, OH and SO3 radicals, which are generated during the aerobic oxidation of sulfite, are particularly suspect as toxic agents. The present proposed research includes three parts: The first part consists of a study of the free radical bleaching of chlorophylls. The next part is to examine the peroxidation of membrane lipids in microsomes, mitochondria and chloroplasts. The third part will involve the in vivo effect of SO2 on metabolism of harvested grapes and the fate of SO2 in the fruit. BIBLIOGRAPHIC REFERENCE: Peiser, G. and Yang, S.F. 1975. Chlorophyll destruction in the presence of bisulfite. Plant Physiol. 56:S-69 (Abstract))